Such devices are known from the background art in the form of universal joints or ball joints, such as for example fixed ball joints, ball-type constant velocity joints and homokinetic joints.
Conventional universal joints comprise two joint forks, which are connectable in each case to a shaft and to one another by a joint part. Universal joints are customarily used in shaft arrangements where torques are transmitted via a plurality of shafts that do not run parallel and/or extend offset by an optionally variable angle to one another. A particular application of universal joints is in articulated shafts for transmitting input forces and steering forces in motor vehicles.
In addition to the above-mentioned universal joints, fixed ball joints are moreover also known from the background art for connecting two shaft sections that do not run parallel, i.e. extend offset by an angle to one another. For example, the documents DE 10 2007 031 078 A1 and DE 10 2007 031 079 A1 disclose ball-type constant velocity fixed joints for input shaft arrangements. These two documents, which from the disclosure content in this respect are extensively identical, disclose ball-type constant velocity fixed joints, in which provided between a joint inner part and a joint outer part are balls that transmit the torque between joint inner part and joint outer part. A type of cage is used to guide the balls. Formed for torque transmission in the joint inner part is longitudinal gearing, into which a shaft section having suitably corresponding external gearing may be inserted.
Such universal joints and fixed ball joints, whilst they fulfil the task of connecting together two shaft sections that are offset at an angle to one another, are unable to meet the current demands for a coupling of two shaft sections that simultaneously damps torsional vibrations. In particular, such joints and/or coupling devices are required to transmit the torques with minimum loss from one shaft section to the other shaft section, but damp vibrations, and in particular torsional vibrations that arise, sufficiently to prevent structure-borne noise that arises for example at the input axle from being transmitted through the vehicle.
In addition to the previously described articulated arrangements in the form of ball joints and universal joints the prior art also includes ball joints that are provided with a damping device. Such a joint is disclosed for example in EP 1 710 459 A1. The articulated arrangement according to EP 1 710 459 A1 that is designed for a steering shaft comprises an outer part in the form of a joint bell, which is associated with a shaft section. An inner part forms a housing part of the ball joint that is connected to a second shaft section. Between the outer part and the semicircular inner part disposed therein an elastic damping layer is provided. The inner part has outwardly oriented projections. The outer part has inwardly oriented projections corresponding to the projections of the inner part. The projections of the outer part and the projections of the inner part engage into one another for torque transmission. The damping layer disposed between the outer part and the inner part connects the projections of the outer part and the inner part to one another.
The elastic damping layer attached to the radial faces of the projections of the inner part and to the corresponding faces of the projections of the outer part, i.e. the damping layer that connects the outer part and the inner part, is subject to high shear stress at these radial faces. In other words, the elastic layer during torque transmission by means of this articulated arrangement, which takes up a relatively large amount of installation space in axial direction, may be sheared off either from the inner part or from the outer part, thereby rendering the function of the articulated arrangement, namely the damping of vibrations, impossible.
DE 41 16 841 A1 discloses an articulated connection between an input bevel gear and an articulated shaft that comprises a flange of a two-part construction. The flange consists of a first flange part, which is associated with the input bevel gear, and a second flange part, which is associated with the articulated shaft. The second flange part is configured as an inner ring that is concentrically surrounded with radial clearance by the first flange part fashioned as an outer ring. The connection of the second flange part to the articulated shaft is effected by means of a homokinetic joint. The second flange part is connected to the homokinetic joint by a screw connections. A torque is transmitted from the articulated shaft to the input bevel gear via the elastic intermediate layer disposed between the two flange parts. The first flange part for this purpose has internal gearing, and on the inner ring of the second flange part corresponding external gearing is formed.
In this articulated arrangement also, the elastic intermediate layer is subject to extreme shear stress, this leading during torque transmission to a shearing-off of the intermediate layer either at the outer ring of the first flange part or at the inner ring of the second flange part and having a negative influence on both the function and the service life of the articulated arrangement. The articulated arrangement according to DE 41 16 841 A1 is moreover of a relatively complex construction with a large number of individual parts. For instance, here a radially outer component of the homokinetic joint is screw-connected to the inner second flange part. The large number of individual parts and the screw connection between the homokinetic joint and the flange part considerably increase the fault liability of this articulated arrangement.
It is an object of the present invention is to provide a torque transmitting device for transmitting torques of the type described in the introduction, which while being of a compact design is simultaneously capable of damping vibrations and transmitting high torques and which both avoids the previously described problems of prior art and also prolongs the service life.